That we in North America face a new kind of threat is beyond question. The attacks against the heartland of the United States, its corporate and military icons, and the killing of over 3,000 civilians, mark a watershed in thinking about security. It is almost two hundred years since civilians in North America have been the object of systematic attack, and even longer since the core of the hegemonic power was struck from the periphery. The important analytical and political questions are What kind of threat do we face? What is the appropriate response to that threat? In other words, what are the appropriate ways to think about dealing with a threat from a nonstate actor with no fixed location or permanently defined territorial assets?